This invention relates to vehicle headliners, a method for forming a vehicle headliner from a thermoformable laminate, and a thermoformable laminate which is useful for making vehicle headliners.
In recent years, automobile manufacturers have been motivated to design vehicle passenger compartments with improved impact absorption panels located at selected areas of the vehicle interior to reduce head injuries to vehicle occupants on account of secondary collisions during an accident. In order to meet or exceed current safety standards (e.g., Federal Motor Vehicle Safety Standard-201), vehicle manufacturers have generally used impact absorbing panels which are formed separately from the vehicle headliner, and which are attached to the vehicle roof and/or the headliner at locations where impact absorption is most needed, such as at the portion of the roof which is adjacent to the upper edge of the windshield, and at areas of the roof near pillars. The production of separate impact absorption units, however, significantly increases manufacturing and assembly costs.
To achieve some savings during the final assembly stages, manufacturers have integrated impact absorption panels into the headliner such as by forming the headliner and impact absorption panels separately, piecing the headliner and impact absorption panels together in a mold with the aid of adhesives, and fusing the pieces together to form a headliner with integrally attached impact absorption panels. The finished headliner with integrally attached impact absorption panels can be installed in a vehicle as a single unit, thereby simplifying vehicle assembly. However, the steps of forming separate impact absorbing panels and integrally attaching the impact absorbing panels to the headliner adds significantly to the cost of the headliner.
Efforts have also been made to form headliners having varying thicknesses and densities depending on the area of the headliner, with relatively thick areas being formed where impact absorption may be important. With such increased thickness, however, the manufacture of the headliner, through a molding process, becomes increasingly complex and expensive.
U.S. Pat. No. 5,823,611 discloses an improved headliner having one or more integrally formed flaps extending from an edge of the headliner and integrally hinged to the edge of the headliner. The flaps are folded over the top of the headliner and concealed in the area between the headliner and vehicle roof. In one embodiment, the flaps are formed of a pleated headliner material to provide a crushable impact absorption material. In another embodiment, higher density headliner material is employed, and the flaps are compressed headliner material which provides a relatively thin high density impact absorption padding. Although the headliners with integrally formed flaps disclosed in U.S. Pat. No. 5,823,611 offer a simple and efficient method of economically providing a vehicle headliner with integrally attached impact absorption panels which meets or exceeds current safety standards, it would be desirable to further simplify production by thermoforming a headliner with integral impact absorption panels, without requiring the additional steps of folding a hinged flap over the top of the headliner and securing it, such as with an adhesive, to the top of the headliner.
The invention provides a thermoformable laminate which can be shaped and compressed in a thermoforming tool to form a vehicle headliner with at least one integral impact absorption area; a method of forming a headliner with at least one integral impact absorption area by heating, shaping and compressing the thermoformable laminate; and the resulting vehicle headliner with at least one integral impact absorption area.
The headliner with integral impact absorption areas meets or exceeds current safety standards for impact absorption (FMVSS-201), while eliminating separate steps associated with preparation of the impact absorption areas, as are required with known methods. In particular, the present invention provides a method of forming a vehicle headliner, having integral impact absorption areas, from a laminate, using a thermoforming technique, thereby eliminating the need for separate impact absorption panels which are subsequently integrated into the roof structure of the vehicle or into the vehicle headliner, and eliminating the need for separate folding and attachment operations subsequent to the thermoforming operation. The invention, therefore, provides a simpler, more economical method of meeting or exceeding current safety standards for impact absorption at the roof area of a vehicle.
The thermoformable laminate of the invention includes a rigid thermoplastic form sheet and a fiber reinforcing layer adhered to each of two opposite faces of the rigid thermoplastic sheet.
The method of forming a vehicle headliner with at least one integral impact absorption area involves the steps of providing a thermoformable laminate including a rigid thermoplastic foam sheet having a thermoforming softening temperature range, a substantially uniform thickness, and a substantially uniform density, and a fiber reinforcing layer adhered to each of two opposite faces of the rigid thermoplastic foam sheet; heating the thermoformable laminate to the thermoforming softening temperature; and shaping and compressing the heated thermoformable laminate to form a headliner having varying thicknesses, including a major portion of the headliner which is relatively thin and highly compressed, and at least one relatively thick, lightly compressed or non-compressed impact absorption area.
The resulting vehicle headliner with at least one integral impact absorption area includes a thermoformed laminate having a unitary, rigid thermoplastic foam sheet which has a major portion which is relatively thin and dense, and at least one relatively thick, lower density impact absorbing area.